In the machining of like parts, such as during a boring operation, the constant wear of the boring tool must be taken into account so as to maintain predetermined dimensions. Also, where conditions exist that cause variant temperatures in the area of the tool, adjustment of the position of the tool relative to the workpiece must be made to compensate for tool movement. Electrical apparatus has been previously developed to make the necessary adjustments. However, such apparatus usually requires complex AC-DC controls used in connection with an electric stepping motor to make the necessary changes in the position of the tool. Such equipment is relatively expensive and extensive maintenance is required to keep such sophisticated equipment running smoothly.